Two-photon Absorption Engineering of 5-(Fluorenyl)-1,10-phenanthroline-based Ru(II) Complexes

This study deals with the fine tuning of the photophysical characteristics, and especially two-photon absorption (2PA) properties, of several homo- and heteroleptic ruthenium(II) complexes involving 5-substituted-1,10-phenanthroline ligands. The 2PA spectra of the complexes were determined in the 700-930 nm range by investigating their two-photon excited luminescence (2PEL). Structure - linear and nonlinear optical properties correlations are discussed, and potential applications (therapy and optical power limiting in the near infrared) can be anticipated.

Fluorescent periodic mesoporous organosilica nanoparticles dual-functionalized via click chemistry for two-photon photodynamic therapy in cells

The synthesis of ethenylene-based periodic mesoporous organosilica nanoparticles for two-photon imaging and photodynamic therapy of breast cancer cells is described.

Solvatofluorochromic, non-centrosymmetric π-expanded diketopyrrolopyrrole

A donor–acceptor type π-expanded diketopyrrolopyrrole behaves as non-centrosymmetric as far as linear optical properties are concerned but as ‘pseudo-symmetric’ for two-photon absorption.

In vitro imaging of β-cells using fluorescent cubic bicontinuous liquid crystalline nanoparticles

Imaging of rat pancreatic β-cells using cubic bicontinuous liquid crystalline nanoparticles loaded with the TB139 fluorescent dye.

Optical and photophysical properties of anisole- and cyanobenzene-substituted perylene diimides

Substituent and solvent effects on the one- and two-photon absorption and the photophysical properties of eight bay-substituted perylene-diimides are reported and analyzed.

trans- and cis-(Cl,Cl)-[RuII(FT)Cl2(NO)](PF6): promising candidates for NO release in the NIR region

Efficient NO photodelivery from cis- and trans-(Cl,Cl)-[Ru^II(FT)Cl₂(NO)](PF₆) complexes upon two-photon excitation in the NIR region.

Two-photon sensitive protecting groups operating via intramolecular electron transfer: uncaging of GABA and tryptophan

Improved photo-labile protecting groups, with high sensitivity to two-photon excitation, are needed for the controlled release of drugs, as tools in neuroscience and physiology. Here we present a new modular approach to the design of caging groups based on photoinduced electron transfer from an electron-rich two-photon dye to an electron acceptor, followed by scission of an ester to release a carboxylic acid. Three different electron acceptors were tested: nitrobenzyl, phenacyl and pyridinium. The nitrobenzyl system was ineffective, giving only photochemical decomposition and no release of the carboxylic acid. The phenacyl system also performed poorly, liberating the carboxylic acid in 20% chemical yield and 0.2% photochemical yield. The pyridinium system was most successful, and was tested for the release of two carboxylic acids: γ-amino butyric acid (GABA) and tryptophan. The caged GABA undergoes photochemical cleavage with a chemical yield of >95% and a photochemical yield of 1%; it exhibits a two-photon absorption cross section of 1100 GM at 700 nm, corresponding to a two-photon uncaging cross section of 10 ± 3 GM.

Two-photon "caging" groups: effect of position isomery on the photorelease properties of aminoquinoline-derived photolabile protecting groups

High two-photon photolysis cross sections and water solubility of probes are important to avoid toxicity in biomedical applications of photolysis. Systematic variation of the position of a carboxyl electron-withdrawing group (EWG) on photolysis of 8-dimethylaminoquinoline protecting groups identified the C5-substituted isomer as a privileged dipole. The 5-benzoyl-8-DMAQ substitution yields a caging group with an enhanced two-photon uncaging cross section (δu = 2.0 GM) and good water solubility (c ≤ 50 mM, pH 7.4).

Enhanced two-photon fluorescence imaging and therapy of cancer cells via Gold@bridged silsesquioxane nanoparticles

A two-photon photosensitizer with four triethoxysilyl groups is synthesized through the click reaction. This photosensitizer allows the design of bridged silsesquioxane (BS) nanoparticles through a sol-gel process; moreover, gold core BS shells or BS nanoparticles decorated with gold nanospheres are synthesized. An enhancement of the two-photon properties is noted with gold and the nanoparticles are efficient for two-photon imaging and two-photon photodynamic therapy of cancer cells.

Dendritic molecular assemblies for singlet oxygen generation: meso-tetraphenylporphyrin-based biphotonic sensitizers with remarkable luminescence

Thanks to its 2-ethynylflorenyl-containing arms, dendrimer 1 sensitizes molecular oxygen in 70% yield and exhibits a fluorescence yield of 20%.

Influence of the synthetic method on the properties of two-photon-sensitive mesoporous silica nanoparticles

The two-photon properties of MSN were studied as a function of the synthetiic method.

Identification of MRC2 and CD209 receptors as targets for photodynamic therapy of retinoblastoma using mesoporous silica nanoparticles

An overexpression of MRC2 and CD209 mannose receptors was revealed in retinoblastoma and antibodies against these receptors were grafted to multifunctional nanoparticles for targeting of imaging and photodynamic therapy.

Strong solvent dependence of linear and non-linear optical properties of donor–acceptor type pyrrolo[3,2-b]pyrroles

The pyrrolo[3,2-b]pyrrole core was determined to be an efficient linker allowing the conjugation of peripheral benzene rings. The resulting dipolar compounds displayed strong solvatochromism of fluorescence.

pKa tuning in quadrupolar-type two-photon ratiometric fluorescent membrane probes

Two ratiometric two-photon pH probes were designed, combining pK_a values close to physiological pH and large two-photon absorption responses. They are able to stain efficiently GUV and cell membranes.

Synthesis of disulfide-based biodegradable bridged silsesquioxane nanoparticles for two-photon imaging and therapy of cancer cells

Biodegradable bridged silsesquioxane nanoparticles for two-photon imaging and therapy of cancer cells are described.

A cyclometallated fluorenyl Ir(iii) complex as a potential sensitiser for two-photon excited photodynamic therapy (2PE-PDT)

A cyclometallated fluorenyl Ir(iii) complex that exhibits enhanced triplet oxygen sensing properties for two photon photodynamic therapy is reported.

Disulfide-gated mesoporous silica nanoparticles designed for two-photon-triggered drug release and imaging

We report two-photon cancer cell killing through mesoporous silica nanogates.

Cooperative dyads for two-photon uncaging

A series of dyads that combine a photolabile protecting group (PPG) 4,5-dimethoxy-2-nitrobenzyl and different bis-donor or bis-acceptor dissymmetric chromophores acting as two-photon (2P) absorbers were synthesized. Even for low energy transfer efficiency from the 2PA subunit to the uncaging one, improvement of the 2P uncaging sensitivity in the NIR is achieved as compared to isolated PPG. Moreover enhancement of the 2PA response is achieved by tuning the electronic dissymmetry of the 2PA subunit and the arrangement of the complementary subunits in the dyads.

Two-photon excitation of porphyrin-functionalized porous silicon nanoparticles for photodynamic therapy

Porous silicon nanoparticles (pSiNPs) act as a sensitizer for the 2-photon excitation of a pendant porphyrin using NIR laser light, for imaging and photodynamic therapy. Mannose-functionalized pSiNPs can be vectorized to MCF-7 human breast cancer cells through a mannose receptor-mediated endocytosis mechanism to provide a 3-fold enhancement of the 2-photon PDT effect.